An image processing apparatus sets a threshold value matrix for each of multiple color materials, and uses the set threshold value matrix to acquire a first threshold value. On the other hand, the image processing apparatus sets reference data on the basis of multivalued data of that color material. Then, the image processing apparatus calculates a second threshold value matrix by performing a predetermined process on the first threshold value on the basis of the reference data for that color material. Further, by comparing the second threshold value with the multivalued data, quantization data for printing a dot is generated. When doing this, the threshold value matrix and the reference data for that color material are set so as to make the graininess of a dot pattern of that color material lower than the graininess of a mixed color dot pattern obtained by mixing dot patterns of the respective multiple color materials.
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1. An image processing apparatus for printing an image on a print medium with use of multiple color materials, the image processing apparatus comprising: a data acquisition unit configured to acquire pieces of multivalued data of a target pixel, the pieces of multivalued data respectively corresponding to the multiple color materials; a threshold value acquisition unit configured to, from among multiple threshold value matrices each configured to include arrayed multiple threshold values, set one threshold value matrix for each of the multiple color materials, and from the set threshold value matrix, acquire a first threshold value corresponding to the target pixel; a reference color setting unit configured to, from among the pieces of multivalued data respectively corresponding to the multiple color materials, set reference data that is referred to in order to perform a predetermined process on the first threshold value acquired by the threshold value acquisition unit for that color material; a calculation unit configured to, for that color material, perform the predetermined process on the first threshold value on a basis of the reference data set by the reference color setting unit and thereby calculate a second threshold value; and a generation unit configured to, for that color material, generate quantization data for printing a dot by comparing a corresponding one of the pieces of multivalued data and the second threshold value, wherein the threshold value acquisition unit and the reference color setting unit set the threshold value matrix and the reference data for that color materials so as to make graininess of a dot pattern of that color material lower than graininess of a mixed color dot pattern obtained by mixing respective dot patterns of the multiple color materials, the dot pattern being determined by the quantization data.
An image processing system for printing uses multiple color inks. It acquires color data for each pixel for each ink. It selects a threshold matrix for each ink, picking a starting threshold value for each pixel. It then sets reference data for each ink based on the color data for that ink, and calculates a new threshold based on the initial threshold and the reference data. Finally, it determines if a dot should be printed for that ink by comparing the color data and the new threshold value. The selection of threshold matrices and reference data is designed so that the individual ink patterns are less grainy than the combined pattern made by mixing the inks.
2. The image processing apparatus according to claim 1 , wherein the predetermined process is a process to be performed such that the quantization data generated by the generation unit on a basis of the second threshold value and quantization data based on the reference data set by the reference color setting unit are mutually exclusive.
The image processing system described previously calculates the new threshold value in such a way that the dot printed based on the new threshold will be placed in a location that will not overlap with the dot that *would* have been printed based on the original reference data. In effect, it makes the new dot printing decision mutually exclusive to what the reference data would have caused. This results in reduced graininess in the printed image.
3. The image processing apparatus according to claim 2 , wherein the predetermined process is a process adapted to offset the first threshold value on a basis of the reference data.
In the image processing system described previously, the new threshold value is derived by offsetting the initial threshold value based on the reference data. In other words, the reference data is used to directly increase or decrease the initial threshold, creating a new threshold that favors printing dots in less grainy configurations.
4. The image processing apparatus according to claim 1 , wherein: the threshold value acquisition unit sets mutually different threshold value matrices for multiple color materials having relatively low lightness among the multiple color materials; and the reference color setting unit sets pieces of reference data to null for the multiple color materials having relatively low lightness.
In the image processing system described previously, different threshold matrices are used for the darker inks, and the reference data is set to 'null' (i.e. ignored) for those darker inks. Specifically, the system uses different threshold matrices for inks with relatively low lightness (darker colors). By setting the reference data to null for these darker inks, the system simplifies the process by not modifying the initial threshold value for those colors.
5. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, and yellow color materials; the threshold value acquisition unit sets a first threshold value matrix for the cyan color material, and sets a second threshold value matrix different from the first threshold value matrix for the magenta and yellow color materials; and the reference color setting unit sets pieces of reference data to null for the cyan and magenta color materials, and for the yellow color material, sets reference data to multivalued data corresponding to the magenta color material.
In an image processing system that uses cyan, magenta, and yellow inks, the system uses one threshold matrix for cyan, and a *different* threshold matrix for magenta and yellow. The reference data for cyan and magenta is set to null. The reference data for yellow is set to the color data value for magenta. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
6. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, and yellow color materials; the threshold value acquisition unit sets a first threshold value matrix for the cyan and yellow color materials, and sets a second threshold value matrix different from the first threshold value matrix for the magenta color material; and the reference color setting unit sets pieces of reference data to null for the cyan and magenta color materials, and for the yellow color material, sets reference data to multivalued data corresponding to the cyan color material.
In an image processing system that uses cyan, magenta, and yellow inks, the system uses one threshold matrix for cyan and yellow, and a *different* threshold matrix for magenta. The reference data for cyan and magenta is set to null. The reference data for yellow is set to the color data value for cyan. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
7. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, and black color materials; the threshold value acquisition unit sets a first threshold value matrix for the black and cyan color materials, and sets a second threshold value matrix different from the first threshold value matrix for the magenta and yellow color materials; and the reference color setting unit sets pieces of reference data for the black and magenta color materials to null, sets reference data for the cyan color material to multivalued data corresponding to the black color material, and sets reference data for the yellow color material to multivalued data corresponding to the magenta color material.
In an image processing system that uses cyan, magenta, yellow, and black inks, the system uses one threshold matrix for black and cyan, and a *different* threshold matrix for magenta and yellow. The reference data for black and magenta is set to null. The reference data for cyan is set to the color data value for black. The reference data for yellow is set to the color data value for magenta. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
8. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, and black color materials; the threshold value acquisition unit sets a first threshold value matrix for the black and magenta color materials, and sets a second threshold value matrix different from the first threshold value matrix for the cyan and yellow color materials; and the reference color setting unit sets pieces of reference data for the black and cyan color materials to null, sets reference data for the magenta color material to multivalued data corresponding to the black color material, and sets reference data for the yellow color material to multivalued data corresponding to the cyan color material.
In an image processing system that uses cyan, magenta, yellow, and black inks, the system uses one threshold matrix for black and magenta, and a *different* threshold matrix for cyan and yellow. The reference data for black and cyan is set to null. The reference data for magenta is set to the color data value for black. The reference data for yellow is set to the color data value for cyan. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
9. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, and light color materials; the threshold value acquisition unit sets a first threshold value matrix for the cyan and light color materials, and sets a second threshold value matrix different from the first threshold value matrix for the magenta and yellow color materials; and the reference color setting unit sets reference data for the cyan and magenta color material to null, sets reference data for the light color material to multivalued data corresponding to the cyan color material, and sets reference data for the yellow color material to multivalued data corresponding to the magenta color material.
In an image processing system that uses cyan, magenta, yellow, and light inks, the system uses one threshold matrix for cyan and light, and a *different* threshold matrix for magenta and yellow. The reference data for cyan and magenta is set to null. The reference data for light is set to the color data value for cyan. The reference data for yellow is set to the color data value for magenta. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
10. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, and light color materials; the threshold value acquisition unit sets a first threshold value matrix for the magenta and light color materials, and sets a second threshold value matrix different from the first threshold value matrix for the cyan and yellow color materials; and the reference color setting unit sets reference data for the cyan and magenta color material to null, sets reference data for the light color material to multivalued data corresponding to the magenta color material, and sets reference data for the yellow color material to multivalued data corresponding to the cyan color material.
In an image processing system that uses cyan, magenta, yellow, and light inks, the system uses one threshold matrix for magenta and light, and a *different* threshold matrix for cyan and yellow. The reference data for cyan and magenta is set to null. The reference data for light is set to the color data value for magenta. The reference data for yellow is set to the color data value for cyan. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
11. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, black, and light color materials; the threshold value acquisition unit sets a first threshold value matrix for the black, cyan, and light color materials, and sets a second threshold value matrix different from the first threshold value matrix for the magenta and yellow color materials; and the reference color setting unit sets pieces of reference data for the black and magenta color materials to null, sets reference data for the cyan color material to multivalued data corresponding to the black color material, sets reference data for the light color material to pieces of multivalued data corresponding to the black and cyan color materials, and sets reference data for the yellow color material to multivalued data corresponding to the magenta color material.
In an image processing system that uses cyan, magenta, yellow, black and light inks, the system uses one threshold matrix for black, cyan and light, and a *different* threshold matrix for magenta and yellow. The reference data for black and magenta is set to null. The reference data for cyan is set to the color data value for black. The reference data for light is set to the color data values for both black and cyan. The reference data for yellow is set to the color data value for magenta. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
12. The image processing apparatus according to claim 1 , wherein: the multiple color materials include cyan, magenta, yellow, black, and light color materials; the threshold value acquisition unit sets a first threshold value matrix for the black, magenta, and light color materials, and sets a second threshold value matrix different from the first threshold value matrix for the cyan and yellow color materials; and the reference color setting unit sets pieces of reference data for the black and cyan color materials to null, sets reference data for the magenta color material to multivalued data corresponding to the black color material, sets reference data for the light color material to pieces of multivalued data corresponding to the black and magenta color materials, and sets reference data for the yellow color material to multivalued data corresponding to the cyan color material.
In an image processing system that uses cyan, magenta, yellow, black and light inks, the system uses one threshold matrix for black, magenta and light, and a *different* threshold matrix for cyan and yellow. The reference data for black and cyan is set to null. The reference data for magenta is set to the color data value for black. The reference data for light is set to the color data values for both black and magenta. The reference data for yellow is set to the color data value for cyan. This arrangement tunes the dot patterns of the different inks against each other for the purpose of reducing the graininess of the overall image.
13. The image processing apparatus according to claim 1 , wherein the threshold value matrices have a blue noise characteristic.
In the image processing system described previously, the threshold value matrices have a blue noise characteristic. Blue noise patterns minimize low-frequency artifacts that can be perceived as graininess in an image.
14. The image processing apparatus according to claim 1 , further comprising a unit configured to print that color material on the print medium in accordance with the quantization data. generates the second quantization data on a basis of the second multivalued data acquired by the acquisition unit and the second threshold value matrix, and (iii) generates the third quantization data on a basis of the second and third pieces of multivalued data acquired by the acquisition unit and the second threshold value matrix.
The image processing system described previously includes a component that prints the dots on the print medium based on the calculated quantization data. The system computes quantization data (dot on/off) based on multiple passes: (i) generate first quantization data from multivalued data and a first threshold value matrix, (ii) generate second quantization data using acquired data and a second threshold value matrix, and (iii) generate third quantization data using acquired data and the second threshold value matrix.
15. An image processing method for printing an image on a print medium with use of multiple color materials, the image processing method comprising: a data acquisition step of acquiring pieces of multivalued data of a target pixel, the pieces of multivalued data respectively corresponding to the multiple color materials; a threshold value acquisition step of, from among multiple threshold value matrices each configured to include arrayed multiple threshold values, setting one threshold value matrix for each of the multiple color materials, and from the set threshold value matrix, acquiring a first threshold value corresponding to the target pixel; a reference color setting step of, from among the pieces of multivalued data respectively corresponding to the multiple color materials, setting reference data that is referred to in order to perform a predetermined process on the first threshold value acquired by the threshold value acquisition step for that color material; a calculation step of, for that color material, performing the predetermined process on the first threshold value on a basis of the reference data set by the reference color setting step and thereby calculating a second threshold value; and a generation step of, for that color material, generating quantization data for printing a dot by comparing a corresponding one of the pieces of multivalued data and the second threshold value, wherein the threshold value acquisition step and the reference color setting step set the threshold value matrix and the reference data for that color material so as to make graininess of a dot pattern of that color material lower than graininess of a mixed color dot pattern obtained by mixing respective dot patterns of the multiple color materials, the dot pattern being determined by the quantization data.
An image processing method for printing uses multiple color inks. It acquires color data for each pixel for each ink. It selects a threshold matrix for each ink, picking a starting threshold value for each pixel. It then sets reference data for each ink based on the color data for that ink, and calculates a new threshold based on the initial threshold and the reference data. Finally, it determines if a dot should be printed for that ink by comparing the color data and the new threshold value. The selection of threshold matrices and reference data is designed so that the individual ink patterns are less grainy than the combined pattern made by mixing the inks.
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July 29, 2016
October 31, 2017
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